May have finally sorted my less than stellar brake performance...

[FLYNAVY30]

Posting this separate from my build thread as it will hopefully help someone else in the future.

My truck is a 1972 C20 Suburban. A few years back, I completely gutted the brake system. It was originally a factory disc/drum set up and the only part that remains is the original pedal itself. I'm using Wilwood D52 calipers with the stock discs on the front, with Wilwood's D52 rear calipers and the rear disc from a square body K20 and a custom bracket from a company that is now out of business. I'm running a Baer 1 1/8 master cylinder and a replacement stock 11" brake booster.

Since I put the system together, it has only worked "OK". The truck stops perfectly straight, but it's always seemed like for any given braking scenario, I needed slightly more force on the pedal than I should have. I recently contact Wilwood about switching to a more aggressive pad compound, and they said that would work, but it would also result in faster pad and rotor wear. The tech made a point of including that they recommend a minimum of 18 in. Hg at idle, and an 8 in. DUAL DIAPHRAGM BOOSTER....

I immediately went out to my truck....showing 15 in. Hg at idle, so not ideal. Then I started doing some research on single vs dual diaphragm boosters. The math to figure out how much "boost" the system is applying is:

(vacuum at idle) x (booster diameter) x (number of diaphragms)

So based on Wilwood's recommendation of 18x8x2, you're looking for 288 "units of boost?"....not sure what that boils down to as far as units. I then did some research, and realized that the '72 trucks came with a SINGLE DIAPHRAGM booster because with the disc/drum set up, you dont want/need as much boost. So running the math on my truck as it sits... 15x11x1 = 165 "units of boost"....obviously well below Wilwood's minimum recommendation for a power brake system. On doing some more research, I quickly realized the '73 trucks, which had 4 wheel disc brakes, came standard with an 11 inch, DUAL DIAPHRAGM booster..... part #2232NB at Summit for $145.99.

So even with my lower vacuum at idle: 15x11x2 puts me at 330 "units of boost" which will hopefully alleviate my lackluster braking performance. I'll report back as soon as I get the new booster in!

-Greg